1. Field of the Invention
The present invention relates to a rotary nozzle of the type which is attached to the bottom of a molten steel vessel, e.g., a laddle or tundish so that a sliding plate brick is rotated and the opening of a nozzle bore of a fixed plate brick is adjusted thereby controlling the pouring rate of molten steel, and more particularly the invention relates to a turning apparatus for a rotor which holds the sliding plate brick.
2. Description of the Prior Art
Rotary nozzles have been used widely with laddles for receiving the molten steel tapped from a converter or the like to transport or to pour the molten steel into molds, tundishes for receiving the molten steel from a laddle to pour the molten steel into molds and the like.
Referring to the accompanying drawings, FIG. 7 is a longitudinal sectional view showing schematically an example of a conventional rotary nozzle, and FIG. 8 is a bottom view of FIG. 7 with a part thereof being omitted. In the Figures, numeral 1 designates a shim plate mounted to the bottom of a laddle, tundish or the like, and 2 a base member attached to the shim plate and formed with a recess for mounting a fixed plate brick 3 therein and an opening into which a top nozzle 5 is fitted. Numeral 6 designates a rotor rotatably arranged on a movable member 11 through a ball bearing 12, formed with a recess in which a sliding plate brick 8 is mounted and an opening into which a bottom nozzle 10 is fitted and provided with a gear 7 on its upper outer periphery thereof. Numeral 13 designates a frame adapted to accommodate the rotor 6 and pivotably attached to the shim plate 1 by a hinge 14. It is to be noted that although not shown, the opposite side to the hinge 14 is secured to the shim member 1 with bolts, levers or the like. Numeral 15 designates springs mounted between the movable member 11 and the frame 13 and they are adapted to press the rotor 6 upward and force the sliding surface of the sliding plate brick 8 into close contact with the fixed plate brick 3.
Numeral 16 designates a motor, 17 a reduction gear, and 18 the final-stage gear of the reduction gear 17 which is in mesh with the gear 7 of the rotor 6.
With the construction described above, the operation of the rotary nozzle will now be described. In the illustrated condition, the nozzle bores of the top nozzle 5, the fixed plate brick 3, the sliding plate brick 8 and the bottom nozzle 10 are located on the same center, and the nozzle bore 9 of the sliding plate brick 8 is in a wide-open position relative to the nozzle bore 4 of the fixed plate brick 3. Therefore, the molten steel in the laddle or the like is poured into a tundish or the like in the maximum amount. To control the rate of pour of the molten steel, the motor 16 is operated so that the rotation reduced by the reduction gear 17 is transmitted to the rotor 6 through the gears 18 and 17, thereby rotating the rotor 6 through a desired angle. When this occurs, the opening of the nozzle bores 4 and 9 is adjusted to control the pouring rate of the molten steel.
Where it is desired to perform the desired maintenance, inspection, etc., or to replace the fixed plate brick 3 and the sliding plate brick 8, it is only necessary to pivotally rotate the frame 13 and the rotor 6 received in the former in a door-like manner by the hinge 14 as a pivot, thus exposing the sliding surfaces.
Rotary nozzles of this type have been recently used in large numbers owing to a number of advantages that the maintenance and inspection are easy, that the damages on the surfaces of the fixed plate brick 3 and the sliding plate brick 8 can be confirmed with the naked eye and they can also be replaced easily and so on.
However, the driving unit for the rotor 6, that is, the motor 16 and the reduction gear 17 which are attached to the bottom of the laddle or the like are extremely large in size and weight thus making it inconvenient to handle.
As a means of solving this difficulty, it is conceivable to rotate the rotor by a hydraulic cylinder or rocking actuator. However, the range of rotation of the rotor is limited by the stroke of the hydraulic cylinder or the rotational angle of the rocking actuator so that in order to increase the rotation range of the rotor, a hydraulic cylinder with a long and strong actuator or a rocking actuator with a large linkage is required and the above-mentioned problem still remains unsolved.